Transfer technology that easily detaches and transfers a thin film with a two-dimensional structure, and strongly attaches the thin film to a desired substrate can be usefully used in various application fields, and generally, to transfer a thin film grown or strongly attached to a substrate onto another substrate, the substrate is removed to separate the thin film, or an adhesive is attached to achieve a stronger bond and then detached. To adhere the detached thin film to a desired substrate, physical (thermal or mechanical compression) methods are primarily used. However, these traditional methods damage or add parts of materials, so they have difficulty in making use of unique properties of the materials.
Such traditional technology is disclosed in Japanese Patent Publication No. 2013-043820A that uses a polymethylmethacrylate (PMMA) film and a PVA film as a transfer support of graphene for the purpose of a low cost and removes the used support using an organic solvent, U.S. Pat. No. 8,906,245B directed to a method of transferring PMMA-coated graphene from a source substrate to a target substrate, including rinsing with deionized water, scooping up with polymer such as sponge, and drying to remove impurities, and similar to these, traditional technology for transfer of a two-dimensional thin film is disclosed in Japanese Patent Publication No. 2014-525134A and Japanese Patent Publication No. 2014-183167A.
Furthermore, Korean Patent No. 1206352B discloses a fabrication method of a flexible substrate including the steps for spreading a carbon ink on a substrate to form a deposition layer, forming a graphene compound layer, and coating a coating solution thereon to form a thin film layer, thereby preventing the flexible substrate from curling.
Where a thin film with a two-dimensional structure is simply adhered through chemical treatment or by the Van der Waals force as disclosed, the adhesive strength with a target substrate is not too high, causing many future problems such as contamination and warping in the manufacture of a device or a component. Particularly, when a polymer material such as PMMA is used as a support for transfer, residues of the used polymer not only deteriorate the unique properties of graphene but also make a transfer step complex, and an additional pyrolysis process takes a long time to remove the residues, and especially, a flexible substrate based on a material with low heat resistance such as a polymer material cannot use a solvent or a pyrolysis process to remove the residues, so in practice, there are various procedural limit conditions.